EQT E-Tuning Q&A

[camel_golf2]

2018 R - Stage 1 91

I can’t seem to figure out why people say it’s normal for hpfp effective vol to reach 100%?

In my case, it seems to happen when I start a pull in 3rd gear and vol % maxes out from ~3700rpm - 5200rpm. At which point my rail pressure gradually drops to 2400psi before recovering (2900psi set point).

Basically I just want to know what to keep an eye out for incase my hpfp or lpfp were to fail. I want to try the e30 file this summer but want to understand the the fueling situation before purchasing.

 

[hans611]

I think we are pretty close to the fueling limit? Mine has a very "mellow" EQT "low torque" Stg2 Protune that only boosts to 24.7psi and my hpfp reaches 96-97% and the lpfp ~92% and it seems to barely hold the 2900psi

https://datazap.me/u/hans611/base-map-wot-3?log=0&data=8-14-18-29-33

 

[camel_golf2]

I think we are pretty close to the fueling limit? Mine has a very "mellow" EQT "low torque" Stg2 Protune that only boosts to 24.7psi and my hpfp reaches 96-97% and the lpfp ~92% and it seems to barely hold the 2900psi

https://datazap.me/u/hans611/base-map-wot-3?log=0&data=8-14-18-29-33

Interesting. I’m assuming with more boost (like an OTS stage 2 file) you would also see your hpfp reach 100%.

Something else that I’m realizing now is that I did this log in cold weather (near freezing) and I’ve read that this is more taxing on the fuel system. Wonder if I relogged with this warmer weather I would still have the same issue.

 

[hans611]

Someone correct me if I am wrong, but I believe the target boost PSI varies, it will only boost higher if it needs more air (when its hot, as the air is less dense, needs more boost)

The fuel requirement should be the same, cold or warm, as the afr will not change... what's nice of cool weather is lower IAT and less chance of knock... So if its really hot, it may pull timing... and then it that case maybe the fuel requirement drops...?

(I think the "driver selected trq" is what sets the requested power and the car decides how much boost it needs... but as long as there isnt any knock, the fuel requirement should be the same?)

 

[Ed @ EQT]

The HPFP is operated via the exhaust cam, so its flow is proportional to RPM (at higher RPM it can hold more pressure and flow more fuel than at lower RPM). Having the HPFP max out and drop some pressure in the mid range is not a problem because there is plenty of injection window available at lower RPM's. The ECU just holds the injector open longer to achieve the same desired fuel flow at a lower pressure. At higher RPM, the injection window is much shorter, so holding pressure becomes more critical.

-- Ed

 

[Ed @ EQT]

Someone correct me if I am wrong, but I believe the target boost PSI varies, it will only boost higher if it needs more air (when its hot, as the air is less dense, needs more boost)

The fuel requirement should be the same, cold or warm, as the afr will not change... what's nice of cool weather is lower IAT and less chance of knock... So if its really hot, it may pull timing... and then it that case maybe the fuel requirement drops...?

(I think the "driver selected trq" is what sets the requested power and the car decides how much boost it needs... but as long as there isnt any knock, the fuel requirement should be the same?)

This is mostly true for a stock tune, but not so much for a performance tune that is trying to maximize power under all conditions. In this type of strategy, the fueling requirement is definitely higher in colder weather.

-- Ed

 

[CaptainRatty]

The HPFP is operated via the exhaust cam, so its flow is proportional to RPM (at higher RPM it can hold more pressure and flow more fuel than at lower RPM). Having the HPFP max out and drop some pressure in the mid range is not a problem because there is plenty of injection window available at lower RPM's. The ECU just holds the injector open longer to achieve the same desired fuel flow at a lower pressure. At higher RPM, the injection window is much shorter, so holding pressure becomes more critical.

-- Ed

This is helpful. My is38 tune (93 octane) drops pressure in the mid-range before eventually catching up in the higher RPM.

 

[hans611]

That's pretty cool that the injectors can compensate for lower rail pressure... would have thought the drop in rail pressure would throw everything off...

 

[camel_golf2]

The HPFP is operated via the exhaust cam, so its flow is proportional to RPM (at higher RPM it can hold more pressure and flow more fuel than at lower RPM). Having the HPFP max out and drop some pressure in the mid range is not a problem because there is plenty of injection window available at lower RPM's. The ECU just holds the injector open longer to achieve the same desired fuel flow at a lower pressure. At higher RPM, the injection window is much shorter, so holding pressure becomes more critical.

-- Ed

What would you consider “higher rpm”?

 

[Ed @ EQT]

That's pretty cool that the injectors can compensate for lower rail pressure... would have thought the drop in rail pressure would throw everything off...

Not at all the case on modern cars, especially DI. DI is set up to work at a very wide range of rail pressures as the pressure is not nearly as stable as a classic PI only system.

-- Ed

 

[Ed @ EQT]

What would you consider “higher rpm”?

Usually over 5500RPM is where injection window starts to become an issue.

-- Ed

 

[Cliff p.]

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[krs]

random question I just thought of today, and couldn’t find a clear answer.

I’m on a E30 tune, do I need to use 91 octane fuel for my blend, or can I use 87 octane for the blend?

 

[Cliff p.]

random question I just thought of today, and couldn’t find a clear answer.

I’m on a E30 tune, do I need to use 91 octane fuel for my blend, or can I use 87 octane for the blend?

Strongly recommend you blend with the highest octane available. If that’s 91 in your area, you should use it to blend.

 

[krs]

Strongly recommend you blend with the highest octane available. If that’s 91 in your area, you should use it to blend.

Cool, that’s what I’ve been doing, and I’ll stick to that.